The present invention relates to an integrated message accounting system for use in a telephone system operating in time frames each consisting of a plurality of time slots.
The use of pulse code modulated (PCM) digital signals in a telephone system enable a multiplicity of conversations to be translated over a two wire digitally multiplexed line commonly known as a T1 trunk line. A T1 trunk line is multiplexed with other T1 lines to form what is known as a line group. The multiplexed PCM data from the line group is then applied to a time slot interchanger for switching the data from one time slot of a line group to a time slot of another line group.
A message accounting system is employed for recording information resulting from toll, long distance and other types of telephone service. Such equipment requires the ability of the system to continuously process telephone calls in progress without disruption to service.
While the use of redundancy is well known for improving the reliability of any data transmission and storage system, redundancy techniques have not been previously employed in major subsystems of an integrated message accounting system to prevent a single point failure which could cause the system to go down.
There is a need for redundancy techniques in an integrated message accounting system where faulty subsystems could be switched automatically off-line to provide minimum interruption to service.
With the advent of microprocessors and electronic solid state design, it is desirable for major subsystems in an integrated message accounting system to utilize microprocessors thereby permitting the subsystems in the message accounting system to operate as independent entities.
In accordance with the above background, there is a need for an improved integrated message accounting system utilizing redundancy techniques and electronic solid state design for use in a telephone system utilizing PCM techniques.